Window alarm switch



Scpt. 26, 1933. 3 PV DAVls 1,928,247

WINDOW ALARM SWITCH Filed June 6, 1952 Patented Sept. 26, 1933 WINDOW ALARM SWITCH George P. Davis, Hattiesburg, Miss., assignor of twenty-seven per cent to Albert O. Mercier,,

Hattiesburg, Miss.

Application June 6, 1932. Serial No. 615,742

4 Claims.

The object of this invention is to provide means whereby an alarm will be operated whenever an unauthorized attempt to open a window is made. The invention is intended primarly for use upon the windows of prisons in which iron bars are inserted and is designed to be operated whenever any bar across a window may be sawed or otherwise divided preliminary to an effort to escape. The invention is illustrated in the accompanying drawing and will be hereinafter first fully described and then more particularly defined.

In the drawing, Figure l is a longitudinal section through a window frame having iron bars across the window opening and having my invention embodied therein,

Fig. 2 is an enlarged detail section on the line 22 of Fig. 1.

In the drawing, the reference numeral 1 designates a portion of a window frame which, in the present instance, is constructed of metal. The frame includes an inner frame 2 defining the window opening and across said opening are shown bars 3 whichare of heavy metal, as is the usual practice. These bars are each secured at one end by a nut 4 which is turned home against an adjacent bar or web of the window frame, the other ends of the bars being disposed within the frame at the opposite side of the window opening and fitting closely through bars or webs 5 disposed within the frame. The last-mentioned ends of the bars are inserted through sleeves 6 which fit tightly about the respective bars and form stems for cups or disks 7 which are held on the bars by nuts 8 turned home against the bases of the cups or the sides of the disks, as will be understood upon reference to Fig. 2. Expansion springs 9 are fitted around the stems 6 between the web or bar 5 and the respective cups or disks 7, and are normally compressed. Extending parallel with the series of cups or disks is a metal bar 10 having its ends secured in end portions of the window frame and insulated therefrom, as indicated at 11, A conductor 12, leading from one side of a battery 13 or other source of electrical energy, is grounded upon the window frame, as indicated at 14, while another conductor 15 has one end secured to an end of the rod or bar 10, as indicated at 16, and extends to one side of a bell 17 or other alarm, the opposite side of the bell being connected with the battery by a conductor 18.

Normally, the springs 9 are compressed and the parts are so proportioned that the cups or disks 7 will be close to but out of contact with the bar 10 and, consequently, the alarm circuit will be broken and the alarm will be quiet. Should any of the bars 3 be sawed through or otherwise divided, the spring 9 cooperating therewith will at once expand and force the disk or cup 7 against the bar 10 so that a circuit will be closed through thebar, the cup and the window frame to sound the alarm. The alarm will continue to sound until the broken bar has been replaced or the circuit is opened by operating a switch in the attendants office. My device is exceedingly simple and is highly efiicient in use. It may be readily applied to any window at a very slight cost and is especially desirable in prisons as the alarm may be located in the oflice of the warden or superintendent so that he will be instantly notified of any attempt to release one or more prisoners.

The invention is particularly shown as being applied to a metal window frame which may be utilized as a part of the alarm circuit, but it will be understood, of course, that it may be applied to wooden window frames in which event it would be necessary merely to extend the conductor 12 so that it would be carried past and attached to each of the sleeves 6 or to a metal washer below each spring 9 whereby the circuit would be closed in exactly the same manner as described. It will be readily noted that the working parts and the conductors are all housed within thev window frames or within the wall of the building so that they cannot be easily tampered with and rendered inoperative.

Having thus described the invention, I claim:- 1. An electrical alarm switch for doors or windows comprising spaced bars adapted to extend across the opening of a door or window, a continuous conductor spaced from and common to all of said bars and insulated from the door or window frame, concave-convex contact members on the outer ends of the bars and having their concave faces normally spaced from the conduc tor, and expansion springs bearing constantly against the convex sides of said contact members whereby upon severance of a selected bar the contact member thereof will be forced directly against the conductor to close a circuit. 1 2. An electrical alarm switch for doors or windows comprising spaced bars adapted to extend across the opening of a door or window and each having one end thereof fixed to the door or window frame, a continuous conductor spaced from and common to all of said bars and insulated from said door or window frame, concavo-convex contact members of greater width than the conductor on the other ends of the bars and having their concave faces normally spaced from the conductor, fastening devices housed within the concave faces of the contact members and engaging the bars for securing said contact members in position thereon, and expansion springs interposed between the convex faces of the contact members and a portion of the door or Window frame and bearing constantly against the convexfaces of the contact members whereby upon severance of a selected bar the peripheral edge of the concave face of the contact member thereof will be forced directly against the conductor to close a circuit.

3. An electrical alarm switch for doors or windows comprising spaced bars adapted to extend across the opening of a door or window, a conductor spaced from and common to all of said bars and insulated from the door or window frame, sleeves fitted to the outer ends of the bars and provided with terminal concavo-convex heads constituting contact members, and expansion springs surrounding the sleeves and interposed between the convex faces of the heads and adjacent portion of the door or window frame and bearing constantly against the convex faces of said contact members whereby upon severance of a selected bar, the peripheral edge of the concave face of the contact member thereof will be forced directly against the conductor to close a circuit.

4. An electrical alarm switch for doors or windows comprising spaced bars adapted to extend across the opening of a door or window and having their outer ends threaded, a conductor common to all of the bars spaced from the threaded ends of said bars and insulated from the door or window frame, sleeves surrounding the threaded ends of the bars and provided with integral concavo-convex heads constituting contact members, nuts engaging the threads on the bars and bearing against the concave faces of the heads and entirely housed within said concave faces, the concave faces of said contact members being normally spaced from the conductor, and expansion springs surrounding the sleeves and each having one end thereof bearing against the convex face of the adjacent head and its other end against the adjacent portion of the door or window frame, said expansion springs bearing against the convex faces of the-contact members whereby upon severance of a selected bar the peripheral edge of the concave face of the contact member thereof will be forced directly against the conductor to close a circuit.

GEORGE P. DAVIS. [L.S.] 

